Oxford Teachers' Club is an online set of very useful resources and tools. The main aim is to support course books published by Oxford University Press, but you can use some of the most useful tools even if you don't use any OUP course materials.

In particular, you can use the Crossword Maker tool. Very regrettably, the excellent Cloze Maker tool has been withdrawn by Oxford, and will not be replaced.

You have to register, but it's free.

https://elt.oup.com/teachersclub/

I've made a short video to show you how to use Crossword Maker. Click on the play arrow to start: you can enter full screen mode at the bottom right.

As noted, Cloze Maker is no longer available, so the video is now outdated in this respect. I'll make a new one that covers just Crossword Maker.